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Engineering crush: Green Roofs

I thought I would write my first ‘spotlight on a technology’ post on…. Green Roofs! It’s because they’re so great. And because I intend to live in a house that has one (if I don’t end up living in a tree house).

What a Green Roof is…

They are multiple layers of soil and plant matter that are installed on the roof of a building. Basically, if all houses and buildings had green roofs, we’d be living in the Shire (minus the hairy feet).

The forest is really good at dealing with storm water. Rain falls on a natural area relatively evenly and it percolates down into the soil. Effectively 100% of the ground is permeable so the water can infiltrate down into the groundwater system (recharging aquifers! Yay!). When an area is built-up, however, rainwater gets erratic. It will run off traditional roofs and onto paved, impermeable sidewalks. If there is no drainage system, flooding will occur. That’s bad. Also, even if there is a drainage system it may be old. Old systems tend to just siphon off the water into nearby lakes or streams. These natural water bodies haven’t been adapted for influxes of large volumes of water. Their delicate stream beds and shores may begin to erode due to the water’s force.

So if you put a little forest on your roof (that’s what a Green Roof effectively is) you can restore the natural process of rainwater movement through our environment. You are protecting streams and lakes! You are helping prevent flooding! You are planting trees and greenery which gobble up CO2! Also, they look pretty boss.

Can I get one?

Yes. I’m glad you asked. There are varying thicknesses of Green Roofs that you can install on your roof. Even a thin layer of soil and plant matter (generally called an “extensive green roof”) can help manage storm water. And it won’t be crazy expensive or require a retrofit to support the added load to your roof.